I would always recommend that they try different things, my build is different from yours and the problem with new tanks is the build is continually changing, so you need to learn what works best for yourself in a given situation. and progress with that.
Learn and understand your own limitations, not others.
Finally something making sense. But I usualy have a few rules against packs.
-I take the big ones and focus one of them, keeping the others away from the healer with my AOE's.
-The DPS are killing the weaker ones alone.
-If a DPS attacks a big one I'm not focusing : I'll let him tank. I will not hold his hand just because he can't focus the good mob.
-Mass mind control is useful when your team decides to use many AOE's, or when a pack spawn during a boss fight and are aiming your healer.
Against bosses :
-I NEVER ASK MY DPS TO HOLD ON, AND I WILL NEVER ASK THEM TO. Well, to be honest there is a single situation where I can ask them to give me a few seconds : when the JM spawns (WH fight in TFB HM), I ask them to not attack the JM untill I'm next to a wall. Mostly because I can't hit him during a few seconds.